Deposition of amorphous carbon nitride thin films using pressure-gradient RF magnetron sputtering and their chemical bonding structures

Amorphous carbon nitride (a-CNx) thin films were deposited through radio frequency (RF) magnetron sputtering under increasing nitrogen gas pressure around a graphite target to provide nitrogen radicals at high concen-trations. The basic properties of the films, mainly chemical bonding structures, were evaluated using X-ray photoelectron spectroscopy (XPS), soft X-ray emission spectroscopy (SXES), and near-edge X-ray absorption fine structure (NEXAFS), and compared with other films deposited through the common sputtering mode, i.e., at a uniform gas pressure in the chamber. To increase the gas pressure around the graphite target, the deposition rate was slightly increased, and the chemical bonding structure of the a-CNx films was changed. However, the ni-trogen content in the a-CNx films obtained from XPS analysis did not increase when the nitrogen gas pressure around the graphite target was increased. The effect of nitrogen incorporation on the a-CNx films was comparatively more effective at higher RF powers. The intensity ratio of sp3-& sigma; and sp2-& sigma; in the SXES spectra of the films increased with increasing RF power, from 85 W to 130 W, then decreased with a further increase in the RF power. This trend was confirmed by the peaks in the C K-edge of the NEXAFS spectra.

Automated summary

In this study, a-CNx thin films were deposited through RF magnetron sputtering with increasing nitrogen gas pressure to provide nitrogen radicals at high concentrations. The films' chemical bonding structures were evaluated using XPS, SXES, and NEXAFS, and compared with films deposited under uniform gas pressure. Increasing the gas pressure around the graphite target slightly increased the deposition rate and changed the chemical bonding structure of a-CNx films. However, the nitrogen content did not increase with the nitrogen gas pressure. The nitrogen incorporation in a-CNx films was more effective at higher RF powers, as indicated by SXES and NEXAFS spectra.